I saw a ST film that had them retreat to a tower/bunker thing.It had some concrete type barricades out the front and I think ended with the troopers fleeing to the roof to await pick up.IIRC it was quite a bad film, however I am trying to find images of the tower thing.I think it had an electric fence/forcefield way out in the perimeter too.

Does anyone know what ST film it was or even better, can you show me some images of said tower please?

I've got the DVD, but not Blu-ray so I can take some screen caps, they won't be superhigh res though.

Doing some quick scanning of the video, there are two structures on the sides of the tower and I'm not sure what they are. One appears to be some sort of crane, but the other looks to just be a very large conduit/pipe. The tower is round and appears to be made from concrete. There are lights that ring the top of the tower, with a squared entry area at the base. There are what appear to be four light poles on the roof and a streamer on each. I'm guessing the idea is that they are wind socks of sorts so that something can land on the roof. On further scanning they are tattered remnants of flags. There are a bunch of concrete barriers/walls around the perimeter of the tower. They are placed at varying distances to create a sort of maze and kill zones. They look to be about 8"-10" thick and vary in height from about 4' to about 10'. They vary in width from what appears to be about 4' to about 10' as well. I'm guessing about 100 yards from the concrete barriers is where the energy fence is located.

The doors and interior appears to be mostly steel construction with large hatch door, like ship and sub hatches.

Unfortunately none of the shots are really great due to the darkness and smoke.